Generator unit for wireless power transfer

ABSTRACT

An RF signal generator wirelessly transferring power to a wireless device includes, in part, a multitude of generating elements generating a multitude of RF signals transmitted by a multitude of antennas, a wireless signal receiver, and a control unit controlling the phases and/or amplitudes of the RF signals in accordance with a signal received by the receiver. The signal received by the receiver includes, in part, information representative of the amount of RF power the first wireless device receives. The RF signal generator further includes, in part, a detector detecting an RF signal caused by scattering or reflection of the RF signal transmitted by the antennas. The control unit further controls the phase and/or amplitude of the RF signals in accordance with the signal detected by the detector.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a Continuation of Ser. No. 14/552,414, filed Nov.24, 2014, entitled “GENERATOR UNIT FOR WIRELESS POWER TRANSFER”, whichclaims the benefit under 35 USC 119 (e) of U.S. provisional ApplicationNo. 61/908,018, filed Nov. 22, 2013, entitled “GENERATOR UNIT FORWIRELESS POWER TRANSFER”, and U.S. provisional Application No.61/920,733, filed Dec. 24, 2013, entitled “ARCHITECTURES FOR GENERATIONUNITS FOR WIRELESS POWER TRANSFER”, the contents of all of which areincorporated herein by reference in their entirety.

The present application is related to and claims the priority benefit ofapplication Ser. No. 14/078,489, filed Nov. 12, 2013, commonly assigned,and entitled “SMART RF LENSING: EFFICIENT, DYNAMIC AND MOBILE WIRELESSPOWER TRANSFER”, the content of which is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

Advances in silicon processing have enabled integration of complexsystems on a single low power chip. The low cost and low powerconsumption of such systems have resulted in proliferation of portableelectronic devices. To operate, such devices must be frequently pluggedinto an electrical outlet to be charged.

Wireless power transmission may be achieved using inductive coupling orelectromagnetic waves. Inductive coupling can deliver power over a shortrange. Electromagnetic (EM) waves may be used to transmit power over alonger distance. Both inductive coupling and EM waves cause analternating current (AC) to be generated at the receiver.

BRIEF SUMMARY OF THE INVENTION

An RF signal generator adapted to wirelessly transfer power to a firstwireless device, in accordance with one embodiment of the presentinvention, includes, in part, a multitude of generating elements adaptedto generate a multitude of RF signals transmitted by a multitude ofantennas, a wireless signal receiver, and a control unit adapted tocontrol the phases of the RF signals generated by the generatingelements in accordance with a signal received by the receiver. Thesignal received by the receiver includes, in part, informationrepresentative of the amount of RF power the first wireless devicereceives from the RF signal generator.

In one embodiment, the control unit is further adapted to control theamplitude of the RF signals generated by the generating elements. In oneembodiment, the RF signal generator is adapted to wirelessly transferpower to the first wireless device using time-domain multiplexing. Inone embodiment In one embodiment, the RF signal generator is furtheradapted to power a second wireless device concurrently with the firstwireless device. In one embodiment, the RF generator is adapted to powerthe first and second wireless devices using time-domain multiplexing.

In one embodiment, the RF signal generator further includes, in part, asecond multitude of generating elements each adapted to generate an RFsignal. The control unit is further adapted to cause either the firstmultitude of generating elements or the second multitude of generatingelements to generate RF signals during a given time period. In oneembodiment, each of the first and second multitude of generatingelements generates an RF signal in accordance with a reference timingsignal supplied by the control unit.

In one embodiment, the RF signal generator further includes, in part, adetector adapted to detect an RF signal caused by scattering orreflection of the RF signal transmitted by the first multitude ofantennas. In one embodiment, the control unit is further adapted tocontrol a phase or amplitude of the RF signal generated by each of thefirst multitude of RF signal generating elements in accordance with thesignal detected by the detector. In one embodiment, the detector isfurther adapted to detect the presence of objects or living organismspositioned along the path of the RF signal transmitted by the firstmultitude of antennas.

In one embodiment, the RF signal generator is integrated on asemiconductor substrate. In one embodiment, the RF signal generator isadapted to receive the second multitude of generating elements in amodular fashion to enable the control unit control the phase oramplitude of the RF signal generated by each of the second multitude ofRF signal generating elements in accordance with the signal the receiverreceives from the first wireless device. In one embodiment, the RFsignal generator further includes, in part, a multitude of controllocked loops adapted to provide timing signals used in varying thephases of the RF signals generated by the RF signal generating elements.In one embodiment, the RF signal generator further includes, in part, amultitude of phase rotators adapted to vary the phases of the RF signalsgenerated by the RF signal generating elements. In one embodiment, thereference timing signal is delivered to the first and second multitudeof generating elements via a tree-like distribution network.

A method of powering a first wireless device using radio frequency (RF)signals, in accordance with one embodiment of the present invention,includes, in part, transmitting a first multitude of RF signals via afirst plurality of antennas, receiving a signal from the first wirelessdevice, and controlling the phases of the first multitude of RF signalsin accordance with the signal received from the first wireless device.The signal received from the first wireless device includes informationrepresentative of an amount of RF power the first wireless devicereceives.

The method, in accordance with one embodiment, further includes, inpart, controlling the amplitudes of the RF signals transmitted by thefirst multitude of antennas in accordance with the signal received fromthe first wireless device. The method, in accordance with oneembodiment, further includes, in part, transmitting the first multitudeof RF signals using time-domain multiplexing. The method, in accordancewith one embodiment, further includes, in part, transmitting a secondmultitude of RF signals to power a second wireless device concurrentlywith the first wireless device. The method, in accordance with oneembodiment, further includes, in part, transmitting the first and secondmultitude of RF signals in accordance with a reference timing signalsupplied by a control unit.

The method, in accordance with one embodiment, further includes, inpart, detecting a scattered RF signal caused by scattering or reflectionof the RF signal transmitted by the first multitude of antennas. Themethod, in accordance with one embodiment, further includes, in part,controlling the phases of the first multitude of RF signals inaccordance with the detected RF signal. The method, in accordance withone embodiment, further includes, in part, detecting the presence ofobjects or living organisms positioned along the path of the firstmultitude of RF signals.

The method, in accordance with one embodiment, further includes, inpart, generating the first multitude of RF signals via a first multitudeof generating elements formed on a semiconductor substrate. Thesemiconductor substrate further including, a receiving unit receivingthe signal from the first wireless device, and a controller controllingthe phases of the first multitude of RF signals. The method, inaccordance with one embodiment, further includes, in part, generatingthe first multitude of RF signals via a first multitude of generatingelements disposed in a generating unit adapted to receive a secondmultitude of generating elements in a modular fashion. The secondmultitude of generating elements generating the second multitude of RFsignals.

The method, in accordance with one embodiment, further includes, inpart, controlling the phases of the first multitude of RF signals inaccordance with a timing signal generated by one or more control lockedloops. The method, in accordance with one embodiment, further includes,in part, controlling the phases of the first multitude of RF signalsusing a multitude of phase rotators. The method, in accordance with oneembodiment, further includes, in part controlling the phases of thefirst and second multitude of RF signals using timing signals deliveredvia a tree-like distribution network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a generation unit adapted to wirelesslytransfer power to a receive unit via radio frequency (RF)electro-magnetic waves, in accordance with one exemplary embodiment ofthe present invention.

FIG. 2 is a block diagram of a generation unit adapted to wirelesslytransfer power to a receive unit via RF electro-magnetic waves, inaccordance with another exemplary embodiment of the present invention.

FIG. 3 is an exemplary computer simulation of the power transmissionefficiency of an RF power generator.

FIG. 4 is an exemplary timing diagram of cycles during which power istransferred from a generating unit to a receive unit, in accordance withone exemplary embodiment of the present invention.

FIG. 5 is an exemplary time-domain multiplexed cycles used to transferpower from a generating unit to a multitude of receive units, inaccordance with one exemplary embodiment of the present invention.

FIG. 6A shows a generating units having disposed therein a multitude ofgenerating elements and a receiver, in accordance with one embodiment ofthe present invention.

FIG. 6B shows exemplary changes in the instantaneous power generated bya generating unit in response to the detection of, a human, a pet, otherenvironmental changes, or conditions, in accordance with one embodimentof the present invention.

FIG. 7 is a schematic diagram of a pair of generating units operatingcooperatively to deliver power wirelessly, in accordance with oneembodiment of the present invention.

FIG. 8 is a schematic block diagram of a generating element, inaccordance with one exemplary embodiment of the present invention.

FIG. 9 is a schematic block diagram of a generating element, inaccordance with one exemplary embodiment of the present invention.

FIG. 10A is a block diagram of a power amplifier disposed in agenerating element and whose power may be varied by changing theresistance of a variable resistor.

FIG. 10B is a block diagram of power amplifier disposed in a generatingelement and whose power may be varied by changing the supply voltage.

FIG. 11 shows an exemplary distribution network distributing referencetiming signals to a multitude of generating unit modules disposed in agenerating unit, in accordance with one exemplary embodiment of thepresent invention.

FIG. 12 is a block diagram of a generation unit module adapted towirelessly transfer power to a receive unit via RF electro-magneticwaves, in accordance with another exemplary embodiment of the presentinvention.

FIGS. 13A-13D show a number of different configurations by which amultitude of generating elements may be arranged to form a generatingunit, in accordance with some exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with embodiments of the present invention, power isadaptively transferred wirelessly from one or more sources ofelectromagnetic waves (also referred to herein as generation units) toone or more receive units (also referred to herein as recovery units ordevices) adapted to convert the received radio-frequencies (RF) EM powerto a direct current (DC) electrical power. Such devices include, forexample, cell phones, tablet computers, electrical toothbrushes,computer mice, security cameras, smoke alarms, measurement equipment inhazardous areas, robots, and the like. Embodiments of the presentinvention transfer power over short or medium ranges in a multitude ofconfigurations, as described further below.

A generation unit, in accordance with one aspect of the presentinvention, is reconfigurable and adaptive to enable the RF power to belocalized in space to maximize power transmission from the generationunit to the receive unit, and minimize RF power loss through radiation.This enables the receive unit to be physically relatively small withoutaffecting the transfer efficiency.

Because a generation unit, in accordance with embodiments of the presentinvention, may be adaptively controlled to vary the path(s) for the RFpower transfer, localization of wireless power transfer is achieved evenin the presence of multi-path effects. The generation unit may befurther adapted to track the receive unit and account for reflectionsoff the obstacles in the surrounding environment.

FIG. 1 is a block diagram of a generation unit (GU) 100 adapted towirelessly transfer power to a receive unit 170 via radio frequency (RF)electro-magnetic (EM) waves, in accordance with one exemplary embodimentof the present invention. GU 100 is shown as including a control unit120, a receiver 150, and a multitude of power generating elements 110 ₁,110 ₂, 110 ₃, 110 ₄ . . . 110 _(N), where N is an integer greater thanone. Control unit 120 is configured to control the operations of thegenerating elements. For example, in one embodiment, control unit 120controls the phase and/or amplitude of the RF signal generated by eachgenerating element 110 _(i) independently, where i is an integer rangingfrom 1 to N. Control unit 120 is also adapted to perform other functionssuch as optimization of the wireless power transfer.

Each generating element 110 _(i) (also referred to as generating element110) is shown as being coupled to an antenna 130 _(i). By adjusting thephase and/or amplitude of the RF signal generated by each generatingelements 110 _(i) independently, control unit 120 causes GU 100 todeliver the RF power in an optimum way, as described below and inapplication Ser. No. 14/078,489, which is incorporated herein byreference in its entirety. In one embodiment, GU 100 is integrated on asemiconductor substrate. Although in FIG. 1 each generating element 110is shown as being associated with an antenna, it is understood that inother embodiments a multitude of generating elements 110 may share thesame antenna with each generating element 110 driving the shared antennaalong a predefined polarization direction. Although in FIG. 1 eachgenerating element 110 is shown as being associated with a singleantenna, it is understood that in other embodiments a generating element110 may be associated with a multitude of antennas.

FIG. 2 is a block diagram of a GU 200 adapted to wirelessly transferpower, in accordance with another exemplary embodiment of the presentinvention. GU 200 is shown as including a control unit 120 and amultitude of power generating unit modules 250 ₁ . . . 250 _(M), where Mis an integer greater than one. Each generating unit module 250 _(i) isshown as including a multitude of generating elements 210 ₁, 210 ₂ . . .210 _(N) where N is an integer greater than one. Each generating unitmodule 250 _(i) is also shown as including an RF signal generationcircuit 215 _(j) wherein j is an integer ranging from 1 to M, a receiver150 _(j) and an optional local control unit 220 _(j). Although in FIG. 2each generating element 210 _(i) (also referred to as generating element210) is shown as being coupled to an associated antenna, it isunderstood that in other embodiments, a multitude of generating elements210 may share the same antenna with each generating element 210 drivingthe shared antenna along a predefined polarization direction. Althoughin FIG. 2 each generating element 210 is shown being as associated witha single antenna, it is understood that in other embodiments agenerating element 210 may be associated with a multitude of antennas.

Control unit 120, which is a master control unit, is adapted to controland vary the phase and/or amplitude of the RF signal generated by eachgenerating element 210 _(i) of each generating unit module 250 _(j)independently via control signal Element_control. Each local controlunit 220 _(j) is adapted to control the operations of generatingelements 210 ₁, 210 ₂ . . . 210 _(N) disposed in that generating unitmodule in response to signal Local_control generated by control unit210. For example, in one embodiment, further optimization of thephase/amplitude of the RF signal generated by the generating elements210 _(i) disposed in a generation unit module (e.g., generation unitmodule 250 ₁) is controlled by the associated local control unit 220_(j) also disposed in that generating unit module (e.g., local controlunit 2201). RF signal generation block 215 _(j) of each generating unitmodule 250, supplies a reference timing signal to generating elements210 ₁, 210 ₂ . . . 210 _(N) disposed in that generating unit in responseto a timing signal supplied by control unit 120. In one embodiment, asdescribed further below, each RF signal generation block 215 _(j) may bea frequency/phase locked-loop, delay locked-loop or any other controllocked-loop or tunable delay circuit that generates a reference timingsignal.

In some embodiments, many of the operations common to generatingelements 210 ₁, 210 ₂ . . . 210 _(N) of each generation unit module 250_(j) are performed, in part, in response to commands/data issued by thegenerating unit's associated local control unit 220 _(j). Accordingly,each generating elements 210 ₁, 210 ₂ . . . 210 _(N) of each generationunit 250 _(j) may be independently controlled either by the localcontrol unit 220 _(j), or control unit 120 common to all generationunits 250 _(j).

In accordance with one aspect of the present invention, by independentlycontrolling the phase and/or amplitude of the RF signal generated byeach generating element 210 ₁, 210 ₂ . . . 210 _(N) (alternatively andcollectively referred to as generating element 210) of each generatingunit module 250 _(j), the RF power transferred to a receive unit 170 maybe maximized.

To achieve such maximization, receive unit 170 transmits a signal to theGU which includes information about the amount of power the receive unitis receiving from the GU. The signal transmitted by the receive unit isreceived by receiver 150 disposed in the GU or in the generating unitmodules disposed in the GU. For example, in one embodiment, as shown inFIGS. 1 and 2, to maintain the optimum power transfer as the receiveunit moves within the range covered by the GU, the receive unitbroadcasts a signal Power_FB that includes a unique identifier assignedto the receive unit as well as information indicative of the amount ofpower the receive unit is receiving. The signal transmitted by thereceive unit may further inform the generating unit that the receiver isin the vicinity of the generating unit and is ready to receive power.The signal transmitted by the receive unit may further identify thereceive unit's device type, such as a robot, a mouse, and the like. Asdescribed further below, the wireless communications between the receiveand generating units may be performed in accordance with any ofcommunications protocols.

The GU receives and uses the information in signal Power_FB toadaptively change the phase and/or amplitude of the RF signalstransmitted by the generating elements 210 to maintain and/or maximizethe power transfer and/or the transfer efficiency to the receive unit.Many conventional algorithms such as the Nelder-Mead, gradient descent,Newton-Raphson, may be used to achieve such optimization.

When powering a single receive unit, and assuming that each generatingelement 210 has a constant impedance, adaptive control of the controlunit 120 may be performed in accordance with a quadratic program with aglobal optimum solution. A number of well-known solutions exist to suchquadratic programs.

For broadcasting information about the received power, a receive unitmay use any wireless communication protocol, either in existence todayor developed in the future. For example, in one embodiment, an IEEE802.11 wireless local area network (WLAN) standard may be used by areceive unit to send a signal to the GU to indicate the power thereceive unit is receiving from the GU. In other embodiments, suchcommunication may be performed using, for example, the Bluetooth,Zigbee, and the like. In yet other embodiments, a GU may operate as aWLAN server to select a receiving element from among a multitude ofreceiving elements to establish communications with. Communicationbetween the GUs to coordinate their operations may also be handled via atwo-way wireless communications network. Such communication links mayalso be used by the receive unit to broadcast the receive unit's ID, andto inform the GUs that the receiver is ready to receive power. Thesignal identifying the receive unit's device type, as well as any othercommunications between the receive unit and the GU(s) may also becarried out using such communications links.

In some embodiment, depending on their physical arrangements andpositions with respect to one another, the generation unit modules maybe caused to transmit power sequentially. In some embodiment, when noreceive unit is detected, the GU is caused to enter a power savings modeduring which no RF signal is transmitted by the GU. FIG. 3 is anexemplary simulation of the power transmission efficiency of an RFsignal as received by an array of 5×3 receive units along differentpositions in the x-y plane. The RF signal generator was simulated toinclude an array of 27×43 generating units positioned 2 meters above thereceive unit. As is seen from FIG. 3, for example, when the generatingunits were simulated to be directly above the receive unit (at the x andy coordinates of 3.8 and 1.7 meters respectively), the power efficiencyis shown to be 0.7.

The amount of RF power generated by a GU may be controlled to optimizetransfer efficiency, meet the power requirements of the receivingelement(s), and/or limit the power reflected off transient objectsand/or living organisms that may be in the path of the transmitted RFsignal, as described further below. Furthermore, in accordance with oneaspect of the present invention, a time-multiplexed technique(time-domain multiplexing) is used to transfer power from a GU to one ormore receive units. In accordance with this technique, when powering asingle receive unit, the GU is controlled so as to generate and transmitpower during certain time periods and not generate power during otherperiods. Accordingly, the average power transferred is controlled by theswitching duty cycle of the RF power generated by the GU.

FIG. 4 is an exemplary timing diagram showing cycles during which poweris transferred from a GU 250 to a receive unit 170. The average powerdelivered to the receive unit is also shown. FIG. 5 is another exemplarytiming diagram showing time-domain multiplexed cycles used to transferpower from GU 250 to three different receive units 170 ₁, 170 ₂ and 170₃. As shown, during the cycles defined substantially by times (t₂-t₁),(t₅-t₄) . . . (t_(2+3k)-t_(1+3k)) power is transferred to the receiveunit 170 ₁, where k is an integer. During the cycles definedsubstantially by times (t₃-t₂), (t₆-t₅) . . . ) . . .(t_(3+3k)-t_(2+3k)) power is transferred to the receive unit 1702.During the cycles defined substantially by times (t₄-t₃), (t₇-t₆) . . .) . . . (t_(4+3k)-t_(3+3k)) power is transferred to the receive unit 170₃. Although not shown explicitly in FIG. 5, it is understood that powercan be transferred to more than one device concurrently during any ofthe timing cycles. In one example, GU 250 may correspond to generatingunit 100 of FIG. 1 or generating unit 200 of FIG. 2.

FIG. 6A shows a GU 275 having disposed therein a number of generatingelements 210 and a detector 190. In accordance with embodiments of thepresent invention, when detector 190 detects movement or senses a changein the amount of power it is detecting, it can adjust the amount ofpower that its associated generating elements generate. Detector 190 isfurther adapted to detect the presence of a human or a pet, in part, inresponse to their heart beat rate. Accordingly, a wireless powergeneration unit, in accordance with embodiments of the presentinvention, is aware of the environment in which it is operating. Forexample, in FIG. 6A, generating unit 275 is assumed to have detected thepresence of a live being (a dog in FIG. 6A) in its transmission path. Inresponse to the detection, the generating unit may either turn off orlower the power of the RF signal it transmits or respond in otherpre-determined and possibly user-customizable ways. Once the generatingunit detects that the dog has moved out of the signal path, it increasesits output power. FIG. 6B shows exemplary changes in the instantaneouspower generated by GU 2750 in response to the detection of, a human, apet or other environmental changes.

Controlling the power delivered via duty-cycling to steer the RF signalto the receive unit(s) provides a number of advantages. First, it causesthe GU(s) to operate at near optimum efficiency at instantaneous fulloutput power. Second, since the power received by the receive units ismaximized during the power delivery cycles, requirements on thesensitivity of the receive unit(s) is relaxed. Furthermore, the poweramplifier disposed in the output stage of each generating element iscaused to possibly operate under less voltage, current and temperaturestresses. Output power generation efficiency is also typically improvedat relatively high instantaneous output power. When using time-domainmultiplexing to transfer power, the total time usable for adaptivelycontrolling the GU is decreased by the duty-cycles. However, since anymovement by the receive unit is often relatively slow, the relativelyslower adaptive feedback control is sufficient. Furthermore, since theduty-cycled transmitted power includes the duty-cycle information, thereceive unit(s) is aware of the duty-cycle and can correctly inform thegenerating unit of the amount of power the receiving unit(s) isreceiving.

In accordance with one aspect of the present invention, thegenerated/transmitted power is changed directly via an output powercontrol technique in each generation element. Controlling the outputpower of each generation element individually enhances the precision offocusing the transmitted power to a point or multiple points in space.Furthermore, compared to the time-domain multiplexing, faster adaptivefeedback control of the generation unit(s) is achieved.

FIG. 7 is shows a multitude of generating units 300 ₁ . . . 300 _(N)that operate in concert to optimize power delivery to a receive device350, in accordance with another embodiment of the present invention.Each generating unit includes, in part, a control unit, a receiver, anda multitude of generating elements, as shown for example in FIGS. 1 and2. The generating units may be mounted in different physical locations.For example, generating unit 300 ₁ may be mounted on a ceiling,generating unit 3002 may be mounted on an adjacent wall of a room,whereas other generating units may be mounted in different rooms orlocations.

In accordance with one aspect of the present invention, the controlunits disposed in the generating units cooperate and implement aprotocol to optimize the power delivery to a receive unit 350. Toachieve this, in accordance with one aspect of the present invention,the generating units establish a communication link and vary the amountof power they generate until the power efficiency they collectivelydeliver to receive unit 350 reaches a maximum. Furthermore, as thereceive device moves from one location to another, a hand-off protocolgoverning the operations of generating units, may select one or moreother generating units that are best positioned to power the receivedevice at its new location. For example, while the protocol may select afirst subset of GU_(s) 300 to power the receive device at its firstposition, as the receive device moves to another location, the protocolmay select a second subset of GU_(s) 300 to power the receive device. Inaccordance with yet another aspect, the control units disposed in thegenerating units establish a communications links to synchronize thereference timing signals that they use to change the phases of the RFsignals they transmit, thereby maximizing the power transfer efficiencyto the receive unit.

FIG. 8 is a schematic block diagram of a generating element 400, inaccordance with one exemplary embodiment of the present invention.Generating element 400 may correspond to generating elements 110 shownin FIG. 1, or generating elements 210 shown in FIG. 2. Generatingelement 400 is shown as including, in part, amplifiers 402, 412, 416, RFchoke/3dB attenuator block 404, transmission line 406, diode 408 andinterstage matching circuit 414. Amplifier 402 amplifies the input RFsignal RFin. RF choke/3dB attenuator block 404 prevents the outputsignal of amplifier 402 from flowing into the bias voltage V_(bias) andreduces performance variations of amplifier 402 due to impedancemismatch In one example, transmission line 406 has an impedance of 70ohms and a round-trip delay of 54°. Transmission line 406 increases thecontrol over the phase shift of the output signal of amplifier 402. Thecapacitance of the reverse-biased diode 408 is also used to control thephase delay of the RF signal. By varying the supply voltage V_(bias),the capacitance of the reverse-biased diode 408 and hence the phasedelay of the RF signal may be varied. Accordingly, transmission line 406together with diode 408 generate the required amount of the phase delayin the RF signal delivered to amplifier 412. In some embodiments, aninductive element may be used in place of diode 408 to vary the phase ofthe RF signal.

Amplifiers 402 and 412 collectively maintain the gain of the RF signalsubstantially independent of the phase introduced by the transmissiongate 406, and diode 408. Interstage match 414 matches the impedance seenat the output of amplifier 412 to the impedance seen at the input ofpower amplifier 416. By varying the voltage supplied by variable voltagesupply Vgate, the amplitude and hence the power of the RF signaltransmitted by amplifier 416 may be varied. Accordingly, generatingelement 400 is adapted to vary both the amplitude and phase of the RFsignal it transmits.

In accordance with one aspect of the present invention, a generationelement includes an RF detector used to detect the output voltagegenerated by a generation element and scattered by the surroundingobjects as well as the voltage generated by any RF signal incident on anantenna coupled to the generation element. During power transmission,this functionality allows for monitoring the phase and the amplitude ofthe generated signal. In the absence of power transmission, powersignals transmitted by other generation elements or their reflectionsoff obstacles, humans or pets can be detected to allow for environmentalawareness of the system. For example, maximum output power can belimited if, for example, humans or pets are detected.

The ability to detect the generated/transmitted output power and/orpower reflected back by objects and/or living organisms has a number ofadvantages, particularly for providing an adaptive or smart solution.For example, transitory or stationary obstacles in the physicalenvironment can be detected to adjust the operation of the GU(s).Moreover, detecting the presence of living organisms allows foradjustment and control of the generated/transmitted power to improveoverall power transmission efficiency and/or respond to userpreferences. Reflections are typically periodic with an organism'sheartbeat, breathing and/or movement, among other factors, and can, forexample, be detected by detecting a Doppler Shift in the reflectedsignal.

FIG. 9 is a schematic block diagram of a generating element 500, inaccordance with another exemplary embodiment of the present invention.Generating element 500 may correspond to generating elements 110 shownin FIG. 1, generating elements 210 shown in FIG. 2 or generating element710 in FIG. 12. The in-phase and quadrature-phase components of theinput RF signal, namely signals RF_in/I and RF_in/Q are bufferedrespectively by buffers 502, 504 and applied to phase rotator andamplitude control block 506, which in turn, changes the phase and/or theamplitude of the received signals in response to signal Ctrl generatedby common digital interface block 550 using, for example, Cartesianaddition. The output signal of phase rotator and amplitude control block506 is buffered by buffer 508, amplified by power amplifier 510 andtransmitted by antenna 418 via output network 512. The amplitude of thetransmitted signal may also be varied by changing the biasing voltageapplied to power amplifier 512 via control signal Power_Ctrl generatedby common digital interface block 550.

Output network 512 is further adapted to detect the RF signal generatedas a result of the scattering and reflection of the RF signal ittransmits, as well as any other RF signal incident on antenna 418. Thescattered signal which may be detected by turning off power amplifier512, is received by the bidirectional input/output terminal I/O ofoutput network 512 and delivered to chopper (chopping circuit) 560.Chopper 560 is adapted to translate the frequency of the RF signal itreceives, such as, for example, by 5 MHz. Using the output signal of thechopper 560, mixer 530 frequency downcoverts the received signal usingthe input RF signal RF_in/I (supplied to the mixer by buffers 502, 530)and supplies the frequency downconverted signal to filter 540. Likewise,using the output signal of the chopper 560, mixer 535 downcoverts thereceived signal using the input RF signals RF_in/Q (supplied to themixer by buffers 504, 532) and supplies the frequency downconvertedsignal to filter 542. Signals Detect_Q_out and Detect_I_out supplied byfilters 540, 542 are representative of the scattered RF signal receivedby antenna 418, and may be further amplified, converted in frequency,and/or converted to digital information, as appropriate, for example byblock 760 described further below and shown in FIG. 12

The output power generated by power amplifier 512 of FIG. 9 may becontrolled in a number of different ways. In FIG. 10A, the amplitude andthus the power of the RF signal generated by amplifier 510 andtransmitted by antenna 360 may be varied by varying the resistance ofvariable resistor 352. In FIG. 10B, the amplitude and thus the power ofthe RF signal generated by amplifier 510 and transmitted by antenna 360may be varied by changing the voltage supplied by of variable supplyvoltage 370. Since the supply voltage may be shared between multipleoutput stages, the circuit shown in FIG. 10B is advantageous incontrolling the power generated by multiple generating elements. Inaddition, the output power generated by amplifier 512 of FIG. 9 may becontrolled by controlling the RF signal input amplitude, for example byusing block 506, as described above.

Each generation element that operates in concert with another generatingelement to provide wireless power requires timing synchronization.Timing synchronization may be provided by the radio-frequency signalsthemselves, or by a separate reference timing signal distributed so asnot to interfere with the RF signals generated by the generationelements. In accordance with one embodiment, a tree-like network is usedto distribute a timing reference signal having a frequency that is asub-harmonic of the RF signal, thereby enabling the use of an integer-Ntype PLL synthesizer to phase-lock both signals. A master referencesignal is used to generate the master timing reference signal. In oneembodiment, the reference signal is buffered and delivered to the firstgeneration element as well as to N_(a) more buffers (e.g., N_(a)=3),which in turn generate a buffered version of the signal for N_(a) morebuffers and an additional generation element. This technique is extendedin a way that a buffered version of the reference signal is distributedto each generating element such that no more than n buffers are used.Distributing the reference signal in accordance with this scheme ensuresthat

$\frac{N_{a}^{n} - 1}{N_{a} - 1}$

generation elements receive the reference signal.

In accordance with another embodiment, the reference timing signal maynot be an exact sub-harmonic of the RF output signal. For example, atiming reference signal at any lower frequency than the RF output signalcan be used by employing a fractional-N phase-locked loop synthesizer. Atiming reference signal at substantially exactly the same as thereference frequency may be employed using injection locking. A timingreference signal at a frequency higher than the RF frequency may bedivided in frequency, either using an integer-N or a fractional-Ndivider.

FIG. 11 shows a reference timing signal generating 600 supplying thereference timing signal REF to generating unit module 250 ₁ via buffer610. Generating unit module 250 ₁ is shown as including a phase-lockedloop (PLL) synthesizer 270 and a multitude of generating elementscollectively identified as 210. The output signal of buffer 610 isfurther buffered by buffers 620 and 630 and supplied to PLL's 270disposed in generating unit modules 250 ₂ and 250 ₃ respectively. Thereference timing signals supplied by buffers 620, 630 are applied toother generating unit modules (not shown).

Each copy of the reference timing signal may be used to generate an RFsignal for a single or a multitude of generating elements, thus allowingfor a modular approach in forming a generating unit. For example, eachgenerating element may have a dedicated phase-locked loop synthesizer togenerate an RF signal whose amplitude and/or delay is controlledindependently, as described above. Alternatively, a multitude ofgenerating elements may use an RF signal generated by the samephase-locked loop synthesizer, as described above with reference to FIG.12.

FIG. 12 is a block diagram of a generating unit module 700, inaccordance with another exemplary embodiment of the present invention.Exemplary generating unit module 700 is shown as including, in part, 12generating elements 710 each coupled to an associated antenna 712.Frequency synthesizer 722, which may be a PLL, receives the referencetiming signal CLK and, in response, generates in-phase (I) andquadrature-phase (Q) components of the RF signal that are applied to thegenerating elements 710 via buffers 720. Shared control interface 750generates the control signals used by the generating elements 710. Forexample, and as described above, control interface 750 generates thecontrol signals that change the phase and/or amplitude of the RF signaltransmitted by each of the antennas 712 to optimize the wireless powerdelivery. Block 760 is adapted to select a pair of in-phase andquadrature-phase signals from among the multitude of pair of signalsDetect_Q_out, Dectect_I_out detected by generating unit elements 700(see FIG. 5), amplify and/or perform additional signal processing (e.g.,chopping) on the selected in-phase and quadrature-phase signals, anddeliver the result of its various operations as an output signalDetect_out. In one embodiment, with the exception of the antennas, allcomponents of generating unit 700 shown in FIG. 12 are formed on anintegrated circuit (IC).

As described above, a generation unit may include one or multiplegenerating unit modules each including, in turn, one or more generationelements, thereby enabling the generating unit to be formed in a modularfashion. The generating unit modules may share a number of componentssuch as the timing reference components, voltage and/or currentreference components, and/or frequency generation components in order toreduce cost, overhead and complexity of the overall generation unit. Themodular approach provides a number of advantages, such as cost savingsdue to economies of scale, the ability to use the same modules for unitsusable in different applications, upgradability, and the like.Consequently, in accordance with embodiments of the present invention,any number of generation elements and/or generating unit modules may becombined in a modular fashion to form a scalable generation unit orsystem.

The higher the number of generation elements and/or generation unitmodules in a generation unit, the higher is the power transferlocalization and overall efficiency. The number of generating elementsand/or generating unit modules may be determined, in part, by the deviceintended to be charged, the requirements for system efficiency, transferrange and accuracy. For example, providing power wirelessly to awireless mouse may have lower requirements on efficiency, range,accuracy and power, and hence would require a relatively fewer number ofgenerating elements and/or generating unit modules than would a tabletcomputer.

A GU, in accordance with embodiments of the present invention, may beformed in a planar arrangement and mounted on the walls and/or ceilingof a room, or placed in any other convenient fashion, to power a receiveunit positioned nearly anywhere inside the room. Furthermore, thegeneration elements, as well as generation unit modules may beconfigured to form an array of generation units in much the same waythat individual antennas may be configured to form an antenna array. Forexample, a two-dimensional planar arrangements of generation elementsand/or generation unit modules may be configured to form a lowform-factor generation units suitable for placement on the walls,ceiling or floors. Three dimensional arrangements of generation elementsand/or generation unit modules may form a spherical or other geometricalshapes that are aesthetically pleasing. The scalability and modularityof the embodiments of the present invention thus provide numerousadvantages.

FIGS. 13A-13D show a number of different configurations by which thegenerating elements, such generating elements 130 of FIGS. 1 and 2, maybe arranged to form a generating unit. In FIG. 13A, generating elements130 are arranged to form a rectangular generating unit 300. In FIG. 13B,the generating elements 130 are arranged to form a circular generatingunit 310. In FIG. 13C, generating elements 130 are arranged to form aspherical generating unit 320. In FIG. 13D, generating elements 130 arearranged to form a cubical generating unit 330.

The above embodiments of the present invention are illustrative and notlimitative. Embodiments of the present invention are not limited by anyRF frequency or any type of antenna, such as dipole, loop, patch, hornor otherwise, used to transmit the RF signal. Embodiments of the presentinvention are not limited by the number of generating elements,generating unit modules, or generating units. Embodiments of the presentinvention are not limited by the polarization direction, such as linear,circular, elliptical or otherwise, of the RF signals transmitted by theantennas. Furthermore, in some embodiments, the transmitted RF signalmay be of varying polarization. While, in accordance with someembodiments, discrete components and/or integrated circuits may be usedto form generating units, generating unit modules or generating blocks,other embodiments may be formed using integrated circuits. Furthermore,in some embodiments, many or all control function may be performed usingone or more FPGAs, microprocessors, microcontrollers, DSPs, ASICs or thelike. Other additions, subtractions or modifications are obvious in viewof the present disclosure and are intended to fall within the scope ofthe appended claims

What is claimed is:
 1. An RF signal generator adapted to wirelesslytransfer power to a first wireless device, said RF signal generatorcomprising: a first plurality of generating elements each adapted togenerate an RF signal, the plurality of the RF signals being transmittedby a first plurality of antennas; a wireless signal receiver; and acontrol unit adapted to control a phase of the RF signal generated byeach of the first plurality of RF signal generating elements inaccordance with a first signal the receiver receives from the firstwireless device, said first signal comprising information representativeof an amount of RF power the first wireless device receives.
 2. The RFsignal generator of claim 1 wherein said control unit is further adaptedto control an amplitude of the RF signal generated by each of theplurality of RF signal generating elements.
 3. The RF signal generatorof claim 1 wherein said RF signal generator is adapted to wirelesslytransfer power to the first wireless device using time-domainmultiplexing.
 4. The RF signal generator of claim 1 wherein said RFsignal generator is further adapted to power a second wireless deviceconcurrently with the first wireless device.
 5. The RF signal generatorof claim 1 wherein said RF generator is further adapted to power asecond wireless device, said RF signal generator transferring power tothe first and second wireless devices using time-domain multiplexing. 6.The RF signal generator of claim 1 wherein said RF signal generatorfurther comprises a second plurality of generating elements each adaptedto generate an RF signal, said control unit being further adapted tocause one of the first plurality of generating elements or the secondplurality of generating elements to generate RF signals during a firsttime period.
 7. The RF signal generator of claim 1 wherein said RFsignal generator further comprises a second plurality of generatingelements each adapted to generate an RF signal, said first and secondplurality of generating elements each adapted to generate an RF signalin accordance with a reference timing signal supplied by the controlunit.
 8. The RF signal generator of claim 1 wherein said RF signalgenerator further comprises: a detector adapted to detect an RF signalcaused by scattering or reflection of the RF signal transmitted by thefirst plurality of antennas.
 9. The RF signal generator of claim 8wherein said control unit is further adapted to control a phase of theRF signal generated by each of the first plurality of RF signalgenerating elements in accordance with the signal detected by thedetector.
 10. The RF signal generator of claim 9 wherein said detectoris further adapted to detect presence of objects or living organismspositioned along a path of the RF signal transmitted by the firstplurality of antennas.
 11. The RF signal generator of claim 1 whereinsaid RF signal generator is integrated on a semiconductor die.
 12. TheRF signal generator of claim 1 wherein said RF signal generator isadapted to receive a second plurality of generating elements in amodular fashion thereby enabling the control unit to control a phase andamplitude of the RF signal generated by each of the second plurality ofRF signal generating elements in accordance with the first signal thereceiver receives from the first wireless device.
 13. The RF signalgenerator of claim 1 further comprising a plurality of control lockedloops adapted to provide timing signals used in varying the phases ofthe RF signals generated by the RF signal generating elements.
 14. TheRF signal generator of claim 1 further comprising a plurality of phaserotators adapted to vary the phases of the RF signals generated by theRF signal generating elements.
 15. The RF signal generator of claim 7wherein said reference timing signal is delivered to the first andsecond plurality of generating elements using a tree-like distributionnetwork.
 16. The RF signal generator of claim 8 wherein said controlunit is further adapted to control the amplitude of the RF signalgenerated by each of the first plurality of RF signal generatingelements in accordance with the signal detected by the detector.
 17. Amethod of powering a first wireless device using radio frequency (RF)signals, the method comprising: transmitting a first plurality of RFsignals via a first plurality of antennas; receiving a first signal fromthe first wireless device; and controlling phases of the first pluralityof RF signals in accordance with the first signal, said first signalcomprising information representative of an amount of RF power the firstwireless device receives.
 18. The method of claim 17 further comprising:controlling amplitudes of the RF signals in accordance with the firstsignal.
 19. The method of claim 17 further comprising: transmitting thefirst plurality of RF signals using time-domain multiplexing.
 20. Themethod of claim 17 further comprising: transmitting a second pluralityof RF signals to power a second wireless device concurrently with thefirst wireless device.
 21. The method of claim 17 further comprising:transmitting a second plurality of RF signals, wherein each of saidfirst and second plurality of RF signals is generated in accordance witha reference timing signal supplied by a control unit.
 22. The method ofclaim 17 further comprising: detecting a scattered RF signal caused byscattering or reflection of the RF signal transmitted by the firstplurality of antennas.
 23. The method of claim 22 further comprising:controlling a phase of the each of the first plurality of RF signals inaccordance with the detected RF signal.
 24. The method of claim 17further comprising: detecting presence of objects or living organismspositioned along a path of the first plurality of RF signals.
 25. Themethod of claim 17 further comprising: generating the first plurality ofRF signals via a first plurality of generating elements formed on asemiconductor substrate, said semiconductor substrate further comprisinga receiving unit receiving the first signal from the first wirelessdevice, said semiconductor substrate further comprising a controllercontrolling the phases of the first plurality of RF signals.
 26. Themethod of claim 17 further comprising: generating the first plurality ofRF signals via a first plurality of generating elements disposed in agenerating unit, said generating unit being adapted to receive a secondplurality of generating elements in a modular fashion.
 27. The method ofclaim 17 further comprising: controlling the phases of the firstplurality of RF signals in accordance with a timing signal generated byat least one control locked loops.
 28. The method of claim 17 furthercomprising: controlling the phases of the first plurality of RF signalsusing a plurality of phase rotators.
 29. The method of claim 17 furthercomprising: controlling the phases of the first plurality of RF signalsusing timing signals delivered via a tree-like distribution network. 30.The method of claim 23 further comprising: controlling an amplitude ofthe each of the first plurality of RF signals in accordance with thedetected RF signal.